Table 1.
Demographic and clinical characteristics of normal controls, ET cases, and PD cases.
| Normal Controls | ET cases | PD cases | p-Value, comparing all 3 groups | p-Value, ET vs. controls | |
|---|---|---|---|---|---|
| N | 120 | 120 | 40 | ||
| Age in years | 70.3 ± 6.0 (70.5) | 69.7 ± 11.1 (71.5) | 68.9 ± 8.0 (71.0) | 0.6 | 0.5 |
| Female gender | 76 (63.3%) | 66 (55.0%) | 14 (35.0%) | 0.007 | 0.2 |
| Disease duration (years)a | NA | 24.8 ± 18.9 (19.0) | 9.3 ± 5.6 (8.5) | <0.001 | NA |
| Years of education | 15.8 ± 2.8 (16.0) | 15.9 ± 2.8 (16.0) | 15.6 ± 3.0 (16.0) | 0.8 | 0.9 |
| Currently married | 70 (58.3%) | 75 (62.5%) | 32 (80%) | 0.05 | 0.5 |
| Current bed-partner | 67 (55.8%) | 83 (69.2%) | 23 (57.5%) | 0.09 | 0.03 |
| Household ratio of persons/room | 0.4 ± 0.2 (0.3) | 0.4 ± 0.2 (0.3) | 0.4 ± 0.3 (0.3) | 0.2 | 0.1 |
| Retired or not employed | 81 (67.5%) | 62.5 (60.7%) | 34 (85.0%) | 0.03 | 0.4 |
| BMI (kg/m2) | 26.8 ± 5.8 (26.1) | 26.3 ± 4.5 (25.8) | 24.5 ± 5.0 (24.1) | 0.05 | 0.8 |
| Caffeine Intake (mg/day)a | 131.7 ± 120.4 (109.4) | 84.3 ± 93.8 (45.6) | 96.7 ± 77.8 (83.7) | 0.002 | 0.001 |
| Alcohol Intake (g/day)a | 7.8 ± 10.4 (3.4) | 8.3 ± 12.0 (4.4) | 4.5 ± 7.7 (1.7) | 0.2 | 0.7 |
| Current cigarette smoker | 8 (6.6%) | 4 (3.3%) | 1 (2.5%) | 0.4 | 0.2 |
| Cigarette pack-years | 12.3 ± 21.1 (0.5) | 13.7 ± 22.2 (0.0) | 8.3 ± 14.0 (1.0) | 0.9 | 0.8 |
| CIRS score | 6.2 ± 3.3 (6.0) | 6.4 ± 3.4 (6.0) | 7.1 ± 3.0 (7.0) | 0.2 | 0.7 |
| MMSE score | 28.7 ± 1.6 (29.0) | 28.9 ± 1.4 (29.0) | 28.5 ± 1.5 (29.0) | 0.4 | 0.4 |
| CESD score ≥10a | 12 (22.2%) | 25 (46.3%) | 17 (31.5%) | <0.001 | 0.05 |
| Medications with sleep effects scoreb | −0.2 ± 0.4 (0.0) | 0.1 ± 0.6 (0.0) | 0.7 ± 0.5 (1.0) | <0.001 | <0.001 |
Data are means ± standard deviations (median) or numbers (percentages).
BMI = body mass index; CIRS = Cumulative Illness Rating Scale; MMSE = Mini-mental State Examination; CESD = Center for Epidemiological Studies Depression Scale; and NA = not applicable.
Cigarette pack-years included data on both smokers and non-smokers.
Variables for which a small proportion (<5%) of subjects have missing data.
Each participant was assigned one of the following three values: 1 = participant takes one or more medications that increases drowsiness; 0 = participant either takes no medications with sleep effects or participant simultaneously takes a combination of medications that stimulate wakefulness and increase drowsiness; −1 = participant takes one or more medications that stimulate wakefulness.